Intraoperative Transrectal Ultrasound Research Articles

Transrectal Ultrasound-Guided Robotic Excision of Perirectal Lymph Node Metastasis After Primary Radical Prostatectomy

Clinical History: A 60-year-old man with prostate specific antigen (PSA) of 10.8 ng/mL underwent a biopsy that showed grade group (GG) 5 adenocarcinoma of the prostate. The MRI showed organ-confined disease although there was an indeterminate 1 cm node in the left anterolateral perirectal fat. During the robotic radical prostatectomy, bilateral extended node dissection was performed, but the perirectal lymph node was not identifiable. Final pathology report confirmed adenocarcinoma GG5, pT2pN0MxR0, 22 lymph nodes were examined. At 3 months follow-up, PSA was 7.5 ng/mL. Diagnosis: Axumin positron emission tomography and computed tomography showed a solitary hot spot at the location of the perirectal node. We discussed treatment options androgen deprivation therapy, radiotherapy, and surgery. The patient elected for perirectal lymph node dissection (LND). In office contrast-enhanced transrectal ultrasound (TRUS) was performed. This confirmed location and visibility for planned intraoperative TRUS-guided excision. Intervention: Robotic LND started between the rectovesical pouch and the anterolateral aspect of the distal rectum. The node was identified with intraoperative TRUS and then a 17F Chiba needle was placed transrectally through the node into the surgical field. Transfixing the node gave direct vision and guided the robotic LND off the rectal wall and surrounding fat. There were no intraoperative complications, operative time was 214 minutes, estimated blood loss minimum, and length of stay 1 day. Follow-Up: Pathology report confirmed two distinct lymph nodes with metastatic prostatic carcinoma with 14- and 3-mm tumor deposit, respectively. PSA has remained undetectable at last follow-up, 40 weeks after LND. Authors do not have any commercial associations during the past 3 years that might create a conflict of interest in connection with the video. Authors have received and archived patient consent for video recording and publication in advance of video recording of procedure. Runtime of video: 5 mins

Vaginoscopic Management of OHVIRA (Obstructive Hemivagina and Ipsilateral Renal Agenesis)

To describe the vaginoscopic management of longitudinal vaginal septum in the case of obstructive hemivagina and ipsilateral renal agenesis (OHVIRA) syndrome. Surgical video describing step-by-step management. OHVIRA syndrome also known as Herlyn-Werner-Wunderlich syndrome is a triad of obstructed hemivagina, uterus didelphys, and ipsilateral renal anomaly [1] (Supplimentary Video 1). Patients usually present after menarche with progressive dysmenorrhea, lower abdominal pain, a paravaginal mass, foul mucopurulent discharge, and intermenstrual bleeding due to hemi hematocolpos [2]. Magnetic resonance imaging is the choice of investigation [3]. Surgical resection of the septum is the choice of treatment, which can be done vaginoscopically to reduce postoperative pain and promote enhanced recovery [4]. In this video, we will demonstrate a case of a 28-years old, nulliparous woman diagnosed with uterine didelphys having lower abdominal pain and persistent vaginal discharge. The video demonstrates the technique of vaginoscopic excision of the right hemi-vaginal septum that resulted in complete visualization of both cervices. Diagnostic laparoscopy confirmed uterine didelphys. The left cervix was visualized and the hysteroscope was negotiated into the cervical canal (Supplimentary Video 2). The left cavity was normal with left ostia. Intraoperative transrectal-ultrasound was done to localize the cystic collection in the right hemivagina. Needle aspiration of cystic collection was done over the bulging portion of the right hemivagina and mucoid material was aspirated. Longitudinal obstructive vaginal septum was incised using a collins knife and mucoid secretions were drained (Supplimentary Video 3). Hysteroscope inserted into opened right hemivagina, negotiated through the right cervix and right hemiuterus with right ostia was visualized. The residual septum was resected with a loop electrode and hemostasis was ensured. Cystoscopy done, left ureteric orifice with urine reflux visualized. Vaginal examination showed both cervices with near normal reconstructed vagina. The possibility of OHVIRA syndrome should be considered in all cases of uterine didelphys. Vaginoscopic management is a safe and effective method with a minimally invasive approach.

Live implant dosimetry may be an effective replacement for postimplant computed tomography in localized prostate cancer patients receiving low dose rate brachytherapy

PurposeTo determine if Live Implant Dosimetry (LIDO) utilizing intraoperative transrectal ultrasound (TRUS) is equivalent to postimplant CT dosimetry (either day 0 or day 30) in patients with localized prostate cancer (PC) treated with low dose rate (LDR) prostate seed brachytherapy. Methods and MaterialsThe treated population consisted of 628 men with localized (T1-T2) PC. All d'Amico risk categories (low, intermediate, and high) were included, and 437 patients were treated with monotherapy (160 Gy) [low and low tier intermediate], and the remainder (191) [high tier intermediate and high risk] with an implant boost (106 Gy) post external beam radiation, to a volume including the prostate and seminal vesicles (46 Gy). LIDO with intraoperative TRUS, postimplant CT (day 0 and day 30) were performed in all cases. Prostate volumes (V), V100 (prostate) and dose (D) D90 (prostate), D30 (urethra), and Rectum D2cc, were recorded. No urinary catheter was used on Day 30 CT. ResultsMore than 91.33% of monotherapy patients reached the target D90 according to LIDO while only 82.99% of Day 0 CT and 92.82% of Day 30 CT achieved target D90. When considering V100, monotherapy patients recorded target dosimetry in 90.93%, 82.31%, and 92.02% of cases assessed by LIDO, Day 0 CT and Day 30 CT, respectively. Strong correlations are observed in D90, Rectum D2cc and Urethra D30 across imaging modalities but V100 and V150 were poorly correlated due to the relative quantification of this parameter and high degree of error in measurement. Of all monotherapy patients with satisfactory dosimetry on LIDO, 94.82% reached target D90 at day 30 CT and 94.19% reached target V100. ConclusionsLIDO and CT are both effective tools for assessing postimplant dosimetry. Patients with satisfactory LIDO dosimetry are highly likely to have equivalent dosimetry on CT at follow-up, indicating that postimplant CT may be eliminated in PC a patients implanted with this technique.

A deep learning method for real-time intraoperative US image segmentation in prostate brachytherapy.

This paper addresses the detection of the clinical target volume (CTV) in transrectal ultrasound (TRUS) image-guided intraoperative for permanent prostate brachytherapy. Developing a robust and automatic method to detect the CTV on intraoperative TRUS images is clinically important to have faster and reproducible interventions that can benefit both the clinical workflow and patient health. We present a multi-task deep learning method for an automatic prostate CTV boundary detection in intraoperative TRUS images by leveraging both the low-level and high-level (prior shape) information. Our method includes a channel-wise feature calibration strategy for low-level feature extraction and learning-based prior knowledge modeling for prostate CTV shape reconstruction. It employs CTV shape reconstruction from automatically sampled boundary surface coordinates (pseudo-landmarks) to detect the low-contrast and noisy regions across the prostate boundary, while being less biased from shadowing, inherent speckles, and artifact signals from the needle and implanted radioactive seeds. The proposed method was evaluated on a clinical database of 145 patients who underwent permanent prostate brachytherapy under TRUS guidance. Our method achieved a mean accuracy of [Formula: see text] and a mean surface distance error of [Formula: see text]. Extensive ablation and comparison studies show that our method outperformed previous deep learning-based methods by more than 7% for the Dice similarity coefficient and 6.9 mm reduced 3D Hausdorff distance error. Our study demonstrates the potential of shape model-based deep learning methods for an efficient and accurate CTV segmentation in an ultrasound-guided intervention. Moreover, learning both low-level features and prior shape knowledge with channel-wise feature calibration can significantly improve the performance of deep learning methods in medical image segmentation.

Comparison of CTVHR and organs at risk contours between TRUS and MR images in IB cervical cancers: a proof of concept study

PurposeTo compare CTVHR and OAR dimensions and inter-rater agreement between magnetic resonance (MR) and trans-rectal ultrasound (TRUS) images in IB cervical cancer patients.MethodsIB cervical cancer patients treated with (chemo)radiotherapy plus MR-guided brachytherapy (BT) were prospectively enrolled in this study. Radiation oncologists contoured CTVHR and OARs in pre-BT MR images (MRI) and intra-operative TRUS images. These contours were subsequently compared in regard to volume and dimension. Contour inter-rater agreement analysis was also investigated using kappa index (KI). Stata 15.0 was used for statistical analysis and a p-value < 0.05 was considered statistically significant.ResultsTRUS CTVHR volumes were statistically smaller than the respective MRI contoured volumes. TRUS CTVHR thickness was found to be consistently smaller than MRI contours in all patients. No statistical difference was seen in width and height between the two different imaging modalities. MRI contours had a median KI of 0.66 (range: 0.56–0.77) while TRUS-based contours had a median KI of 0.64 (range: 0.47–0.77). Bladder and rectum had very satisfactory KI in both imaging modalities. Vaginal contours had moderate agreement in MR (0.52) and in TRUS images (0.58).ConclusionTRUS images allow good visualization of CTVHR and OARs in IB cervical cancer patients. Inter-rater contour variability was comparable between TRUS and MR images. TRUS is a promising modality on its own for image-guided BT.

Deformable registration of PET/CT and ultrasound for disease-targeted focal prostate brachytherapy.

We propose a deformable registration algorithm for prostate-specific membrane antigen (PSMA) PET/CT and transrectal ultrasound (TRUS) fusion. Accurate registration of PSMA PET to intraoperative TRUS will allow physicians to customize dose planning based on the regions involved. The inputs to the registration algorithm are the PET/CT and TRUS volumes as well as the prostate segmentations. PET/CT and TRUS volumes are first rigidly registered by maximizing the overlap between the segmented prostate binary masks. Three-dimensional anatomical landmarks are then automatically extracted from the boundary as well as within the prostate. Then, a deformable registration is performed using a regularized thin plate spline where the landmark localization error is optimized between the extracted landmarks that are in correspondence. The proposed algorithm was evaluated on 25 prostate cancer patients treated with low-dose-rate brachytherapy. We registered the postimplant CT to TRUS using the proposed algorithm and computed target registration errors (TREs) by comparing implanted seed locations. Our approach outperforms state-of-the-art methods, with significantly lower ( ) TRE of while being computationally efficient (mean computation time of 38s). The proposed landmark-based PET/CT-TRUS deformable registration algorithm is simple, computationally efficient, and capable of producing quality registration of the prostate boundary as well as the internal gland.

Fusion of Intraoperative Transrectal Ultrasound Images with Post-implant Computed Tomography and Magnetic Resonance Imaging.

PurposeTo compare the impact of the fusion of intraoperative transrectal ultrasound (TRUS) images with day 30 computed tomography (CT) and magnetic resonance imaging (MRI) on prostate volume and dosimetry.Methods and materialsSeventy-five consecutive patients with CT and MRI obtained on day 30 with a Fast Spin Echo T2-weighted magnetic resonance (MR) sequence were analyzed. A rigid manual registration was performed between the intraoperative TRUS and day-30 CT based on the prostate volume. A second manual rigid registration was performed between the intraoperative TRUS and the day-30 MRI. The prostate contours were manually modified on CT and MRI. The difference in prostate volume and dosimetry between CT and MRI were compared.ResultsProstate volume was on average 8% (standard deviation (SD) ± 16%) larger on intraoperative TRUS than on CT and 6% (18%) larger than on MRI. In 48% of the cases, the difference in volume on CT was > 10% compared to MRI. The difference in prostate volume between CT and MRI was inversely correlated to the difference in D90 (minimum dose that covers 90% of the prostate volume) between CT and MRI (r = -0.58, P < .001). A D90 < 90% was found in 5% (n = 4) on MRI and in 10% (n = 7) on CT (Fisher exact test one-sided P = .59), but in no patient was the D90 < 90% on both MRI and CT.ConclusionsWhen fusing TRUS images with CT and MRI, the differences in prostate volume between those modalities remain clinically important in nearly half of the patients, and this has a direct influence on how implant quality is evaluated.

Prostate CT segmentation method based on nonrigid registration in ultrasound-guided CT-based HDR prostate brachytherapy.

The technological advances in real-time ultrasound image guidance for high-dose-rate (HDR) prostate brachytherapy have placed this treatment modality at the forefront of innovation in cancer radiotherapy. Prostate HDR treatment often involves placing the HDR catheters (needles) into the prostate gland under the transrectal ultrasound (TRUS) guidance, then generating a radiation treatment plan based on CT prostate images, and subsequently delivering high dose of radiation through these catheters. The main challenge for this HDR procedure is to accurately segment the prostate volume in the CT images for the radiation treatment planning. In this study, the authors propose a novel approach that integrates the prostate volume from 3D TRUS images into the treatment planning CT images to provide an accurate prostate delineation for prostate HDR treatment. The authors' approach requires acquisition of 3D TRUS prostate images in the operating room right after the HDR catheters are inserted, which takes 1-3 min. These TRUS images are used to create prostate contours. The HDR catheters are reconstructed from the intraoperative TRUS and postoperative CT images, and subsequently used as landmarks for the TRUS-CT image fusion. After TRUS-CT fusion, the TRUS-based prostate volume is deformed to the CT images for treatment planning. This method was first validated with a prostate-phantom study. In addition, a pilot study of ten patients undergoing HDR prostate brachytherapy was conducted to test its clinical feasibility. The accuracy of their approach was assessed through the locations of three implanted fiducial (gold) markers, as well as T2-weighted MR prostate images of patients. For the phantom study, the target registration error (TRE) of gold-markers was 0.41 ± 0.11 mm. For the ten patients, the TRE of gold markers was 1.18 ± 0.26 mm; the prostate volume difference between the authors' approach and the MRI-based volume was 7.28% ± 0.86%, and the prostate volume Dice overlap coefficient was 91.89% ± 1.19%. The authors have developed a novel approach to improve prostate contour utilizing intraoperative TRUS-based prostate volume in the CT-based prostate HDR treatment planning, demonstrated its clinical feasibility, and validated its accuracy with MRIs. The proposed segmentation method would improve prostate delineations, enable accurate dose planning and treatment delivery, and potentially enhance the treatment outcome of prostate HDR brachytherapy.

A New CT Prostate Segmentation for CT-Based HDR Brachytherapy.

High-dose-rate (HDR) brachytherapy has become a popular treatment modality for localized prostate cancer. Prostate HDR treatment involves placing 10 to 20 catheters (needles) into the prostate gland, and then delivering radiation dose to the cancerous regions through these catheters. These catheters are often inserted with transrectal ultrasound (TRUS) guidance and the HDR treatment plan is based on the CT images. The main challenge for CT-based HDR planning is to accurately segment prostate volume in CT images due to the poor soft tissue contrast and additional artifacts introduced by the catheters. To overcome these limitations, we propose a novel approach to segment the prostate in CT images through TRUS-CT deformable registration based on the catheter locations. In this approach, the HDR catheters are reconstructed from the intra-operative TRUS and planning CT images, and then used as landmarks for the TRUS-CT image registration. The prostate contour generated from the TRUS images captured during the ultrasound-guided HDR procedure was used to segment the prostate on the CT images through deformable registration. We conducted two studies. A prostate-phantom study demonstrated a submillimeter accuracy of our method. A pilot study of 5 prostate-cancer patients was conducted to further test its clinical feasibility. All patients had 3 gold markers implanted in the prostate that were used to evaluate the registration accuracy, as well as previous diagnostic MR images that were used as the gold standard to assess the prostate segmentation. For the 5 patients, the mean gold-marker displacement was 1.2 mm; the prostate volume difference between our approach and the MRI was 7.2%, and the Dice volume overlap was over 91%. Our proposed method could improve prostate delineation, enable accurate dose planning and delivery, and potentially enhance prostate HDR treatment outcome.

Automatic Localization of the da Vinci Surgical Instrument Tips in 3-D Transrectal Ultrasound

Robot-assisted laparoscopic radical prostatectomy (RALRP) using the da Vinci surgical system is the current state-of-the-art treatment option for clinically confined prostate cancer. Given the limited field of view of the surgical site in RALRP, several groups have proposed the integration of transrectal ultrasound (TRUS) imaging in the surgical workflow to assist with accurate resection of the prostate and the sparing of the neurovascular bundles (NVBs). We previously introduced a robotic TRUS manipulator and a method for automatically tracking da Vinci surgical instruments with the TRUS imaging plane, in order to facilitate the integration of intraoperative TRUS in RALRP. Rapid and automatic registration of the kinematic frames of the da Vinci surgical system and the robotic TRUS probe manipulator is a critical component of the instrument tracking system. In this paper, we propose a fully automatic registration technique based on automatic 3-D TRUS localization of robot instrument tips pressed against the air-tissue boundary anterior to the prostate. The detection approach uses a multiscale filtering technique to identify and localize surgical instrument tips in the TRUS volume, and could also be used to detect other surface fiducials in 3-D ultrasound. Experiments have been performed using a tissue phantom and two ex vivo tissue samples to show the feasibility of the proposed methods. Also, an initial in vivo evaluation of the system has been carried out on a live anaesthetized dog with a da Vinci Si surgical system and a target registration error (defined as the root mean square distance of corresponding points after registration) of 2.68 mm has been achieved. Results show this method's accuracy and consistency for automatic registration of TRUS images to the da Vinci surgical system.

Towards ultrasound probe positioning optimization during prostate needle biopsy using pressure feedback

Accurate Transrectal Ultrasound (TRUS)-guided prostate needle biopsy requires registering preoperative 3D TRUS or MR image, in which tumors and other suspicious areas are visible, to intraoperative 2D TRUS images. Such image registration is time-consuming while its real-time implementation is yet to be developed. To bypass this registration step, robotic needle biopsy systems can be used to place the US probe at the same position relative to the prostate during the 3D and 2D image acquisition to ensure similar prostate deformation. To have such similar deformation, only visual feedback is not sufficient as such feedback can be used to only guarantee that the whole prostate is within the field of view irrespective of the probe's orientation. As such, contact pressure feedback can be utilized to ensure consistent minimum contact between the probe and prostate. A robotic system is proposed where a TRUS probe with pressure sensor array is used. The contact pressure can be measured during imaging and used to provide feedback in conjunction with an optimization algorithm for consistent probe positioning. The robotic system is driven by the feedback to position the probe such that pressure pattern of the sensors during 2D image acquisition is similar to the pressure pattern during 3D image acquisition. The proposed method takes into account the patient's body movement expected during image acquisition. In this study, an in silico phantom is used where the simulated contact pressure distribution required in the optimization algorithm is obtained using a prostate finite element model. Starting from an arbitrary position where the probe contacts the phantom, this position was varied systematically until a position corresponding to maximum pressure pattern similarity between contact pressure patterns corresponding to the 2D and 3D imaging was achieved successfully. Results obtained from the in silico phantom study indicate that the proposed technique is capable of ensuring having only minimal relative prostate deformation between preoperative image acquisition and intraoperative imaging used for guiding needle biopsy, paving the way for faster and more accurate registration.

High-Dose-Rate Interstitial Brachytherapy as Monotherapy for Clinically Localized Prostate Cancer: Treatment Evolution and Mature Results

To report the clinical outcome of high-dose-rate (HDR) interstitial (IRT) brachytherapy (BRT) as sole treatment (monotherapy) for clinically localized prostate cancer. Between January 2002 and December 2009, 718 consecutive patients with clinically localized prostate cancer were treated with transrectal ultrasound (TRUS)-guided HDR monotherapy. Three treatment protocols were applied; 141 patients received 38.0 Gy using one implant in 4 fractions of 9.5 Gy with computed tomography-based treatment planning; 351 patients received 38.0 Gy in 4 fractions of 9.5 Gy, using 2 implants (2 weeks apart) and intraoperative TRUS real-time treatment planning; and 226 patients received 34.5 Gy, using 3 single-fraction implants of 11.5 Gy (3 weeks apart) and intraoperative TRUS real-time treatment planning. Biochemical failure was defined according to the Phoenix consensus, and toxicity was evaluated using Common Toxicity Criteria for Adverse Events version 3. The median follow-up time was 52.8 months. The 36-, 60-, and 96-month biochemical control and metastasis-free survival rates for the entire cohort were 97%, 94%, and 90% and 99%, 98%, and 97%, respectively. Toxicity was scored per event, with 5.4% acute grade 3 genitourinary and 0.2% acute grade 3 gastrointestinal toxicity. Late grade 3 genitourinary and gastrointestinal toxicities were 3.5% and 1.6%, respectively. Two patients developed grade 4 incontinence. No other instance of grade 4 or greater acute or late toxicity was reported. Our results confirm IRT-HDR-BRT is safe and effective as monotherapy for clinically localized prostate cancer.

Robotic Transrectal Ultrasonography During Robot-Assisted Radical Prostatectomy

We evaluate the use of robotically manipulated transrectal ultrasound (TRUS) for real-time monitoring of prostate and periprostatic anatomy during robot-assisted prostatectomy (RAP). Ten patients with clinically organ-confined prostate cancer undergoing RAP underwent preoperative and real-time intraoperative biplanar TRUS evaluation using a robotically manipulated TRUS device (ViKY System; EndoControl Medical, Grenoble, France). Median patient age was 66 yr (range: 54–88), baseline prostate-specific antigen (PSA) was 5.3 (range: 1.3–17.9), and four patients (40%) had clinical high-grade and high-stage disease. Bilateral or unilateral nerve sparing was performed in nine patients (90%). Median time for ViKY System setup to insertion of the TRUS probe was 7min (range: 4–12). Complete robotic TRUS evaluation was successful in all patients. Five patients (50%) had TRUS-visible hypoechoic lesions, confirmed cancerous on preoperative biopsy. Relevant intraoperative TRUS findings were relayed in real time to the robotic surgeon, particularly during dissection of the bladder neck and prostatic apex, during neurovascular bundle preservation, and when hypoechoic prostate lesions approximated nerve-preserving dissection. Negative margins were achieved in nine patients (90%), including cases where significant intraprostatic lesions abutted or extended through the prostate capsule. No complications occurred. We concluded that real-time robotic TRUS guidance during RAP is feasible and safe. Robotic TRUS can provide the console surgeon with valuable anatomic information, thus maximizing functional preservation and oncologic success.

Haptic Simulator for Prostate Brachytherapy with Simulated Needle and Probe Interaction

This paper presents a haptic simulator for prostate brachytherapy. Both needle insertion and the manipulation of the transrectal ultrasound (TRUS) probe are controlled via haptic devices. Tissue interaction forces that are computed by a deformable tissue model based on the finite element method (FEM) are rendered to the user by these devices. The needle insertion simulation employs 3D models of needle flexibility and asymmetric tip bevel. The needle-tissue simulation allows a trainee to practice needle insertion and targeting. The TRUS-tissue interaction simulation allows a trainee to practice the 3D intraoperative TRUS placement for registration with the preoperative volume study and to practice TRUS axial translation and rotation for imaging needles during insertions. Approaches to computational acceleration for realtime haptic performance are presented. Trade-offs between accuracy and speed are discussed. A graphics-card implementation of the numerically intensive mesh-adaptation operation is also presented. The simulator can be used for training, rehearsal, and treatment planning.

Prostate volume measurement by transrectal ultrasound and computed tomography before and after permanent prostate brachytherapy

Purpose To quantify prostate volume (pvol) changes with transrectal ultrasound (TRUS) immediately after permanent prostate brachytherapy (PPB) and to correlate these changes with postimplant computed tomography (CT) volumetrics. To provide data relevant to evaluating the potential of TRUS-based image fusion for intraoperative dosimetry. Methods and materials Between July 2000 and January 2003, 177 patients underwent 125I PPB monotherapy at our institution, and 165 patients provided research authorization. A total of 136 patients (82%) completed 4 imaging studies: planning TRUS, intraoperative pre- and postimplant TRUS, and CT. Results Mean planning TRUS pvol was 38.7 ± 11.7 cc standard deviation (SD), 95% confidence interval (CI) (36.7, 40.7). Mean intraoperative TRUS pvol preimplant was 37.1 ± 11.7 cc SD, 95% CI (35.1, 39.0), and postimplant was 44.5 ± 15.1 cc SD, 95% CI (42.0, 47.1). The mean ratio of postimplant:preimplant intraoperative TRUS pvols was 1.2 ± 0.2 SD, 95% CI (1.18, 1.24), and the difference in mean values was 7.5 cc ( p < 0.0001). CT performed within 1 day revealed a mean pvol of 47.9 ± 15.7 cc SD, 95% CI (45.2, 50.5). The mean volumetric ratio of CT to postimplant TRUS pvol was 1.13 ± 0.36, 95% CI (1.07–1.19). Conclusions Whereas mean preimplant step-section TRUS pvol measurements are similar, postimplant TRUS and CT measurements have greater variability that depend on initial pvol. CT-based pvol measurements determined a mean of 10.6 hours after implant were more likely to be identical to those of immediate postimplant TRUS in prostates >33 cc. These data are relevant for establishing accuracy in image-fusion based approaches being investigated for real-time intraoperative PPB dosimetry.

REAL-TIME TRANSRECTAL ULTRASONOGRAPHY DURING LAPAROSCOPIC RADICAL PROSTATECTOMY

We describe the technical aspects of real-time transrectal ultrasound (TRUS) monitoring and guidance during laparoscopic radical prostatectomy (LRP). Furthermore, we describe the TRUS visualized anatomy of periprostatic structures during LRP. In 25 consecutive patients undergoing transperitoneal LRP, baseline preoperative, real-time intraoperative and immediate postoperative TRUS evaluations were performed. To define periprostatic anatomy precisely TRUS measurements were obtained with specific reference to the neurovascular bundle (NVB), prostate apex, membranous urethra, bladder neck, rectal wall and any cancer nodule. Conventional gray scale, power Doppler, harmonic imaging and 3-dimensional ultrasound functions were used. Real-time TRUS navigation facilitated 3 technical aspects of LRP. 1) It identified the correct plane between the posterior bladder neck and prostate base, allowing quick laparoscopic identification of the vasa and seminal vesicles. 2) It identified the occasional, difficult to see distal protrusion of the prostate apex posterior to the membranous urethra, thus enhancing apical dissection with negative margins. 3) It provided visualization of any hypoechoic nodule abutting the prostate capsule, alerting the laparoscopic surgeon to perform wide dissection at that location. TRUS measured various anatomical parameters including i) the mean distance +/-SD between the NVB and the lateral edge of the prostate a) at apex (1.9 +/- 0.9 mm), b) base (2.5 +/- 0.8 mm) and c) tip of seminal vesicle (4.0 +/- 1.6 mm), ii) the dimensions of the NVB a) before (4.5 x 3.9 mm), b) after (4.2 x 3.6 mm) nerve sparing LRP and c) after nonnerve sparing LRP (0.9 x 0.9 mm), iii) arterial blood flow resistive index within NVB a) before (0.83 +/- 0.04), b) after (0.84 +/- 0.03) nerve sparing LRP and c) after nonnerve sparing LRP (0), iv) and the length of membranous urethra a) before (12.2 +/- 1.1 mm) and b) after (11.7 +/- 1.0 mm) surgery. Focal distortion of the prostate surface by an exophytic nodule was visualized on TRUS in 3 patients, necessitating ipsilateral nerve resection at LRP and contributing to negative surgical margins. This initial experience suggests that real-time intraoperative TRUS guidance may enhance anatomical performance of LRP. This improved understanding of periprostatic anatomy has the potential to improve functional and oncological outcomes. Such corroboration is awaited.

Transperineal radiofrequency interstitial tumor ablation of the prostate: Correlation of magnetic resonance imaging with histopathologic examination

Objectives Radiofrequency (RF) energy has recently been employed to destroy human tissue in vivo. The purpose of this study was to investigate the safety of this approach in localized carcinoma of the prostate (CaP) and specifically, the predictability of lesions obtained with radiofrequency interstitial tumor ablation (RITA). Methods Using RITA, a total of 21 lesions were induced in 10 patients with localized CaP (mean age 70.4 years). RF was delivered transperineally under transrectal ultrasound (TRUS) guidance. All patients underwent endorectal magnetic resonance imaging (MRI) before and after treatment. Radical prostatectomy was performed in all patients 1 to 7 days after RITA. Three of the patients were treated with local anesthesia only. The predictability of the thermal lesion was assessed by correlating the findings of intraoperative TRUS, preand post-RITA endorectal MRI, and the histologic examination of the specimen. Results Postoperatively, patients were catheterized for an average of 1.8 days (1 to 3 days). Lesions of 2 × 2 × 2 cm were targeted. Average lesion diameters obtained on MRI were 2.08 ± 0.23 × 2.09 ± 0.36 × 2.28 ± 0.21 cm. Average lesion diameters defined by coagulative necrosis at histologic examination were 2.20 ± 0.23 × 2.10 ± 0.31 × 2.38 ± 0.14 cm. There were no statistically significant differences ( P = 0.377) between average lesion volume on MRI (5.37 ± 1.83 cm 3) and average lesion volume at histology (5.86 .63 cm 3). No complications or adverse events were noted. Conclusions In this Phase I study, RITA was shown to be safe and feasible, and to result in lesions that were predictable in size and location. MRI accurately visualized and verified the area of coagulative necrosis as documented at histology. The procedure is technically simple and can even be performed under local anesthesia.

Salvage radical prostatectomy after failed transperineal cryotherapy: histologic findings from prostate whole-mount specimens correlated with intraoperative transrectal ultrasound images

Objectives This study evaluates the potential for salvage radical prostatectomy after failure of transrectal ultrasound (TRUS)-guided percutaneous cryosurgical ablation of the prostate. An additional purpose was to determine the accuracy of intraoperative TRUS to delineate the extent of freeze destruction that results from cryosurgery. Methods Six patients with biopsy-confirmed, Stage T3 prostate cancer underwent salvage radical prostatectomy 3 to 10 months after failing prostate cryosurgery. Zones of freeze destruction (resolving coagulative necrosis) and residual adenocarcinoma were mapped on the coverslips of whole-mount sections. Histologically proven zones of freeze destruction correlating to successfully treated prostatic tissue were compared to the hypoechoic ice ball treatment zones seen on intraoperative TRUS images. Results The whole mounts were found to contain necrotic areas of cryodestruction that appeared much smaller than predicted by intraoperative ultrasound. Each of the cases also contained residual viable adenocarcinoma. All patients are alive and clinically free of localized disease 0.5 to 12 months after salvage radical prostatectomy. Conclusions Salvage radical prostatectomy offers an effective treatment option in patients who have failed transperineal cryosurgery of the prostate. Intraoperative TRUS predicted that the entire prostate would show freeze destruction. Whole-mount analysis, however, revealed areas of remaining unaffected adenocarcinoma and normal prostatic parenchyma. TRUS, therefore, overestimates the area of prostatic tissue destroyed by extreme cold. This finding challenges the assumption that the entire prostate is lethally frozen when its boundaries are included within the hypoechoic ice ball witnessed on TRUS.